Longer Combination Trucks: Potential Infrastructure Impacts, Productivity
Benefits, and Safety Concerns (Chapter Report, 08/09/94,
GAO/RCED-94-106).
The Intermodal Surface Transportation Efficiency Act of 1991 directed
GAO to report on the economic and safety impact of multiple-trailer
trucks, known as longer combination vehicles (LCV). Most LCVs are
either triple or double trailers that operate at gross weights above the
80,000-pound federal limit allowed on interstate highways, primarily in
14 western states that have "grandfathered" exemptions from the federal
weight limits, and on some turnpikes in six other states. While the
analyses of benefits from and costs attributable to LCVs are theoretical
because of different assumptions, wider use of these combination trucks
would reduce annual trucking costs, according to one analysis, by about
3 percent or $3.4 billion. Meanwhile, analyses by the Federal Highway
Administration indicate that nationwide use of LCVs on the interstate
highway system could require additional investments of $2.1 billion to
$3.5 billion to replace bridges, improve interchanges, and provide
staging areas for the breakdown and assembly of these vehicles. While
limited data on LCVs show they have not been a safety problem where used
in western states and on eastern turnpikes, GAO has previously
identified operational characteristics of LCVs that could make them a
greater safety risk if allowed on more congested highways.
--------------------------- Indexing Terms -----------------------------
REPORTNUM: RCED-94-106
TITLE: Longer Combination Trucks: Potential Infrastructure
Impacts, Productivity Benefits, and Safety Concerns
DATE: 08/09/94
SUBJECT: Trucking operations
Freight transportation operations
Cost control
Transportation costs
Transportation safety
Shipping industry
Highway safety
Motor vehicles
Traffic regulation
Safety regulation
IDENTIFIER: Alaska
Arizona
Colorado
Florida
Idaho
Indiana
Kansas
Massachusetts
Montana
Nebraska
Nevada
New York
North Dakota
Ohio
Oklahoma
Oregon
South Dakota
Utah
Washington
Wyoming
FHwA National Bridge Inventory
FHwA Motor Carrier Safety Assistance Program
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Cover
================================================================ COVER
Report to Congressional Committees
August 1994
LONGER COMBINATION TRUCKS -
POTENTIAL INFRASTRUCTURE IMPACTS,
PRODUCTIVITY BENEFITS, AND SAFETY
CONCERNS
GAO/RCED-94-106
Longer Combination Trucks
Abbreviations
=============================================================== ABBREV
AAR - Association of American Railroads
AASHTO - American Association of State Highway Transportation
Officials
DOT - Department of Transportation
FHWA - Federal Highway Administration
FRA - Federal Railroad Administration
GAO - General Accounting Office
ISTEA - Intermodal Surface Transportation Efficiency Act
LCV - longer combination vehicle
LTL - less-than-truckload
Letter
=============================================================== LETTER
B-256723
August 9, 1994
Congressional Committees
This report on the economic impact of longer combination vehicles
(LCVs) is our final report in response to the Intermodal Surface
Transportation Efficiency Act of 1991 (P.L. 102-240), which directed
us to report on the economic and safety impact of LCVs on shared
highways. The act froze LCV routes to those existing on June 1,
1991. As agreed with your Committees' staff, this report discusses
the potential costs that might be incurred and benefits that might
accrue if the use of LCVs were expanded. It also summarizes the
findings of our two previous reports that addressed safety concerns.
This report contains matters for congressional consideration.
We are sending copies of this report to the Secretary of
Transportation; the Administrators of the Federal Highway
Administration and the Federal Railroad Administration; the Director,
Office of Management and Budget; and interested congressional
committees and subcommittees. We will make copies available to
others upon request.
This work was performed under the direction of Kenneth M. Mead,
Director, Transportation Issues, who can be reached on (202) 512-2834
if you or your staff have any questions. Major contributors to this
report are listed in appendix III.
Keith O. Fultz
Assistant Comptroller General
List of Committees
The Honorable Max S. Baucus
Chairman
The Honorable John H. Chafee
Ranking Minority Member
Committee on Environment
and Public Works
United States Senate
The Honorable Ernest F. Hollings
Chairman
The Honorable John C. Danforth
Ranking Minority Member
Committee on Commerce, Science,
and Transportation
United States Senate
The Honorable Norman Y. Mineta
Chairman
The Honorable Bud Shuster
Ranking Minority Member
Committee on Public Works
and Transportation
House of Representatives
EXECUTIVE SUMMARY
============================================================ Chapter 0
PURPOSE
---------------------------------------------------------- Chapter 0:1
At least 14 states and six turnpike authorities permit limited
operation of long multiple-trailer trucks known as longer combination
vehicles (LCV). LCVs transport cargo at less cost than shorter
combination vehicles because fewer drivers and tractors are needed
and less fuel is used. Some sectors of the trucking industry would
like the Congress to permit a wider use of LCVs. However, concerns
have been raised that expanding the use of LCVs would increase
highway costs and pose a threat to traffic safety.
The Intermodal Surface Transportation Efficiency Act of 1991 directed
GAO to report on the economic and safety impact of LCVs. This report
focuses on the economic impacts, including (1) the impacts on
infrastructure--pavements, bridges, and interchanges--that might
result from expanded LCV operations and (2) the potential benefits
from and industry's use of LCVs. This report also summarizes GAO's
two previous reports on LCV safety issues in order to comprehensively
discuss LCVs in one report.
BACKGROUND
---------------------------------------------------------- Chapter 0:2
The most common LCVs are triples (a third 28-foot trailer added to
two others), turnpike doubles (a second long trailer added to a 45-
or 48-foot single), and Rocky Mountain doubles (a short trailer added
behind a long one). LCVs normally operate at gross weights well
above the 80,000-pound federal limit allowed on interstate highways
primarily in 14 western states that have used "grandfather"
exemptions from the 80,000-pound limit. Turnpike authorities in six
other states also allow some LCV operations. The 1991 act froze LCV
routes to those existing on June 1, 1991.
RESULTS IN BRIEF
---------------------------------------------------------- Chapter 0:3
While generating benefits in the form of lower transportation costs,
LCVs could also generate costs for public authorities who provide and
pay for the infrastructure used by the trucking industry. The
analyses of the benefits from and costs attributable to LCVs have
been somewhat theoretical because of the various assumptions used to
analyze available data. LCVs would probably not increase pavement
wear, but according to the Federal Highway Administration's (FHWA)
analyses, nationwide use of LCVs on the interstate highway system
could require additional investments of $2.1 billion to $3.5 billion
to replace bridges, improve interchanges, and provide staging areas
for the breakdown and assembly of LCVs. Much of the projected
infrastructure costs would be incurred in the more densely populated
areas of the country. If LCV expansion were limited to carefully
selected routes away from major population areas, the cost impact
would be limited, but the benefits would also be reduced.
An analysis for the trucking industry projected that nationwide use
of LCVs on interstate and some primary highways would reduce annual
trucking costs by about 3 percent ($3.4 billion). As annually
recurring benefits, these would exceed the one-time infrastructure
investment costs estimated by FHWA. However, expansion of the routes
open to LCVs would benefit some sectors of the trucking industry more
than others. One sector, the large companies that consolidate
packages or shipments under 10,000 pounds, could benefit immediately
from even a partial expansion of LCV routes. These companies have
extensive terminal networks for the collection and distribution of
shipments, and they use triple 28-foot trailers for trips between
terminals, known as linehauls. The truckload sector, which moves
cargo by the trailerload from a shipper's dock to a receiver's dock,
might use double 48-foot trailers if a national network of highways
were open to them. In the absence of such a network, large truckload
companies have not adjusted their mode of operation to accommodate
doubles.
Any decision to allow the expanded use of LCVs involves safety
concerns as well as economic factors. The limited data available on
the safety record of LCVs show that they have not been a safety
problem on the western highways and eastern turnpikes where they
currently operate. However, GAO's previous reports identified
operational characteristics of LCVs that could make them a greater
safety risk than single-trailer combinations if allowed on
more-congested highways.
PRINCIPAL FINDINGS
---------------------------------------------------------- Chapter 0:4
LCVS COULD INCREASE
INFRASTRUCTURE COSTS IF
ALLOWED NATIONWIDE
-------------------------------------------------------- Chapter 0:4.1
Because LCVs spread their higher gross weight over more axles, they
generally do not increase pavement wear relative to shorter
combinations and may actually be less damaging. However, the higher
gross weight of LCVs (especially turnpike doubles) can pose a load
capacity problem for some bridges. Because bridges are designed to
support much higher loads than expected, there is room for
disagreement on the margin of safety deemed necessary for loads on a
bridge. At GAO's request, FHWA provided two different estimates of
the number of bridges considered inadequate for LCV use and the cost
to replace them. The Association of American Railroads, which views
turnpike doubles as a threat to rail business, favors using a
conservative bridge capacity rating to estimate the potential impact
of LCVs. When FHWA used this rating, the analysis projected
replacement costs of over $5 billion for rural interstates and over
$13 billion for urban interstates. The second analysis, using a
capacity rating considered by FHWA to be closer to that used in most
states, projected $248 million for rural interstates and $1.1 billion
for urban interstates.
In addition to bridge replacements, nationwide use of LCVs would
require improvements to some interchanges as well as the provision of
staging areas adjacent to interstate highways where LCVs could be
assembled and broken down. The cost depends on how many points of
access to the interstate system are deemed necessary for effective
LCV operations. In 1985, FHWA estimated these access costs at
between $750 million and $2.2 billion. A later study sponsored by
the trucking industry questioned whether such extensive access was
really needed. It also noted that many of the access problems were
in densely populated eastern states and that current states that
allow LCVs already provided staging areas or let the private sector
provide its own.
Several analyses have projected that LCVs (mainly turnpike doubles)
would divert freight from railroads to highways, increasing trucking
ton-miles from 5 to 16 percent. Most of these results were derived
from a computer simulation model maintained by the Association of
American Railroads; however, GAO believes that the model has
significant shortcomings. Most importantly, the model makes no
allowance for ongoing productivity gains by the railroads, which have
been substantial in recent years. These gains have made the
railroads more capable of preserving their market share against
trucking competition. The model also assumes that the truckload
sector will generally convert to using turnpike doubles, which is
unlikely if LCV routes are expanded selectively.
BENEFITS AND INDUSTRY'S
POTENTIAL USE OF LCVS
-------------------------------------------------------- Chapter 0:4.2
According to a study done for the trucking industry, opening the
interstate system and some primary highways to LCVs would lower
annual trucking costs by $3.4 billion (about 3 percent). If the
expansion of LCV routes were limited to highways with low traffic
density, the potential benefits would be lower and would apply mostly
to companies that use triple 28-foot trailers to transport
consolidated small shipments between terminals. These
less-than-truckload and package companies make extensive use of
double 28-foot combinations, which are legal nationwide, and add a
third trailer wherever these additions are legal.
On the other hand, companies that sell by the trailerload would have
to change their mode of operation to use turnpike doubles. These
truckload companies' drivers often travel from shipper's dock to
receiver's dock to another shipper's dock and so on until arriving at
home. Such an operation is relatively simple with single-trailer
combinations but would be more complex with turnpike doubles.
Because turnpike doubles would be limited mainly to interstate
highways, companies would have to organize pickup and delivery at a
customer's dock by single trailer. In the current fragmented system
of LCV routes, truckload companies have not found it practical to
organize such operations.
SAFETY CONCERNS MAY JUSTIFY
LIMITS ON LCV EXPANSION
-------------------------------------------------------- Chapter 0:4.3
GAO has previously reported that LCVs have operational
characteristics, such as trailer sway, that make maneuvering in
traffic more challenging than for single-trailer vehicles. Although
the data on LCV safety are quite limited, available data do not show
that LCVs have been a safety problem in the areas of low traffic
density where they currently operate. Trucking industry officials
agree that to minimize the safety risks, LCVs need well-qualified
drivers as well as proper loading and brake adjustment. However, GAO
previously reported that most states that allow LCVs do little to
monitor their operations, regulate drivers' qualifications, or
inspect the vehicles. Considering these factors, any expansion of
LCV routes should be subject to careful analysis and accompanied by
better state supervision of LCV operations.
MATTERS FOR CONGRESSIONAL
CONSIDERATION
---------------------------------------------------------- Chapter 0:5
Considering the need for additional infrastructure investment and the
uncertainties about the safety of LCVs, GAO believes that if the
Congress wishes to allow the expanded use of LCVs, it should
authorize the Secretary of Transportation to consider exceptions to
the freeze on LCV expansion only if requested by states and
accompanied by the following:
A state analysis of each proposed route to demonstrate its
suitability in terms of the density of traffic, condition of
bridges, and adequacy of interchanges. States should determine
whether additional infrastructure costs would be generated and
how these costs would be recovered.
A certification that the state will enforce qualification standards
for LCV drivers, ensure adequate inspection of LCV equipment,
and monitor the experience of LCVs to identify any emerging
safety problems or negligent carriers.
AGENCY COMMENTS
---------------------------------------------------------- Chapter 0:6
GAO provided copies of the draft report to Department of
Transportation (DOT) officials, who chose to provide oral comments.
GAO met with various DOT officials, including the Director, Office of
Engineering and Highway Operations Research and Development, FHWA,
and the Chief, Office of Economic Analysis, Federal Railroad
Administration. These officials generally agreed with the report's
findings, conclusions, and matters for congressional consideration.
They gave GAO editorial and technical suggestions for clarifying and
qualifying the report, which have been included in the text where
appropriate. FHWA's Administrator has recently stated that FHWA
would thoroughly reexamine all commercial vehicle size and weight
issues.
INTRODUCTION
============================================================ Chapter 1
Some states allow trucking companies to use long multiple-trailer
combinations known as longer combination vehicles (LCVs). LCVs can
transport a given amount of cargo at less cost than shorter
combinations because fewer tractors and drivers are needed and less
fuel is used. Some trucking companies favor the expansion of LCV
routes to increase productivity. However, concerns have been raised
that expanding LCV use would increase infrastructure costs and pose a
threat to traffic safety. We have issued two previous reports on LCV
safety issues.\1
The most common LCVs are triples (a third 28-foot trailer added to
two others), turnpike doubles (a second long trailer added to a 45-
or 48-foot single), and Rocky Mountain doubles (a short trailer added
behind a long one.) Figure 1.1 illustrates these LCVs and
distinguishes them from combinations allowed to operate nationwide.
Trucking companies, particularly in the West, also use variations of
these configurations (particularly different types of trailers) for
special transportation needs.
Figure 1.1: Distinguishing
LCVs From Other Trucks
(See figure in printed
edition.)
Source: American Trucking Associations and Transportation Research
Board.
--------------------
\1 Truck Safety: The Safety of Longer Combination Vehicles Is
Unknown (GAO/RCED-92-66, Mar. 11, 1992) and Longer Combination
Trucks: Driver Controls and Equipment Inspection Should Be Improved
(GAO/RCED-94-21, Nov. 23, 1993).
LCVS CURRENTLY OPERATE IN
LIMITED AREAS
---------------------------------------------------------- Chapter 1:1
Since 1974, federal law has limited gross vehicle weight on
interstate highways to 80,000 pounds. However, 14 western states
have allowed LCVs to operate at heavier gross weights under
"grandfather" exemptions from the federal law. In addition, turnpike
authorities in six other states allow some LCV operations. LCVs are
often restricted to interstate highways, but Oregon allows triples on
many state roads, and western states generally allow Rocky Mountain
doubles to operate widely. Figure 1.2 shows 14 western states and
six turnpike authorities that allow LCVs, and table 1.1 shows the LCV
types that are authorized in those states. The Intermodal Surface
Transportation Efficiency Act (ISTEA) required the Federal Highway
Administration (FHWA) to identify state regulations allowing LCV
operations as of June 1, 1991. FHWA officials said that by using the
technical definition of an LCV stated in ISTEA, their final rule will
include some additional states allowing LCVs to operate, and would
not include Florida because its turnpike is not designated as part of
the interstate system.
Figure 1.2: States and
Turnpike Authorities Allowing
LCVs
(See figure in printed
edition.)
Table 1.1
LCV Configurations Permitted by 14
States and Six State Turnpike
Authorities
Turnpike Rocky Mtn.
States Triples doubles doubles
--------------- ------------- ------------- -------------
Alaska \a 1984 1984
Arizona\b 1976 1976 1976
Colorado 1983 1983 1983
Idaho 1968 1968 1968
Montana 1987 1972 1968
Nebraska\c 1984 1984 1984
Nevada 1969 1969 1969
North Dakota 1983 1983 1983
Oklahoma 1987 1986 1986
Oregon 1967 \a 1982
South Dakota 1988 1984 1981
Utah 1975 1974 1974
Washington \a \a 1983
Wyoming \a \a 1983
State turnpike
authorities
Florida \a 1968 1968
Indiana 1986 1956 1956
Kansas 1960 1960 1960
Massachusetts \a 1959 1959
New York \a 1959 1959
Ohio 1990 1960 1960
------------------------------------------------------------
Note: Years shown are years in which the LCV type was first
permitted.
\a Not permitted.
\b Arizona permits LCVs on one interstate crossing the northwest
corner of the state.
\c Nebraska permits LCVs only with empty trailers.
LCV EXPANSION IS CURRENTLY
FROZEN BY LAW
---------------------------------------------------------- Chapter 1:2
ISTEA froze LCV routes to those existing on June 1, 1991. If the
freeze were lifted, states with grandfather rights allowing trucks to
exceed the 80,000-pound limit on interstate highways could designate
additional LCV routes or allow combinations that they had not
previously permitted.\2 States without grandfather rights could not
allow any trucks to exceed the 80,000-pound limit unless the Congress
authorized new exceptions.
--------------------
\2 An attorney for FHWA believes that some states may have exceeded
their authority to issue permits for LCV operations and that if the
freeze were lifted, FHWA might challenge the right of states to allow
LCV expansion.
TRUCKING INDUSTRY
CHARACTERISTICS
---------------------------------------------------------- Chapter 1:3
The use of LCVs varies within the trucking industry, and consequently
it is useful to recognize some of the divisions and characteristics
within the industry. One major division is between private fleets
and companies that offer for-hire trucking. Private fleets serve the
needs of their parent companies, such as manufacturers, retailers,
etc. They account for about half of intercity trucking tonnage. We
found private fleets using both turnpike doubles and Rocky Mountain
doubles, and in some situations triples might suit a private fleet's
purposes.
Among the companies offering trucking for hire, several distinctions
are important. Package companies handle very small shipments, while
less-than-truckload (LTL) companies handle a range of larger
shipments. The package and LTL companies have similar operations:
they collect, sort, consolidate, transport, and distribute shipments
through a dense network of terminals organized on the hub-and-spoke
principle. These companies have come to prefer 28-foot trailers
because of their flexibility in organizing shipments throughout their
terminal networks. For example, a double 28-foot combination may
leave Chicago with one trailer loaded for the company's terminal in
Cleveland and another loaded for its terminal in Harrisburg,
Pennsylvania. These companies often use triple 28-foot combinations
where they are legal.
Customers shipping full trailerloads over 10,000 pounds to a
destination generally employ truckload companies. Much of the
truckload business is general freight carried in dry van trailers,
but specialized segments include refrigerated vans, intermodal
containers, tankers, flatbed trailers, automobile carriers, and
household movers. Although truckload companies may have some regular
round trips in some corridors, it is not uncommon for their drivers
to travel progressively from shipper's dock to receiver's dock to
another shipper's dock and so on until eventually arriving back home.
This is especially true for large companies carrying general freight
and operating nationwide. Truckload companies use 48-foot and
53-foot trailers, and the latter trailer is becoming more and more
numerous. The truckload industry includes a host of small companies,
many of which serve specialized markets or travel only a few routes.
There are also many "owner-operators," who own a truck and may
operate under contract to other companies or accept loads from
freight brokers. The truckload sector is thus much more diverse than
the LTL and package sectors. LCVs most appropriate to general use in
the truckload sector would be turnpike doubles, if a national highway
network were open to them. In the absence of such a network, some
companies in the West have found a variety of uses for Rocky Mountain
doubles.
OBJECTIVES, SCOPE, AND
METHODOLOGY
---------------------------------------------------------- Chapter 1:4
ISTEA directed us to report on the economic and safety impact of LCVs
on shared highways. We discussed safety issues in two previous
reports. This report focuses on the economic impact of LCVs,
including (1) the infrastructure impacts--on pavements, bridges, and
interchanges--that might result from expanded LCV operations and (2)
the potential use and benefits of LCVs. In order to provide an
overall perspective on factors to be considered in permitting LCV
operations, chapter 4 summarizes our two previous reports on LCV
safety issues.
In reviewing the potential impact of LCVs on the infrastructure, we
reviewed existing studies and interviewed officials of FHWA, the
Federal Railroad Administration (FRA), the Transportation Research
Board, the American Association of State Highway and Transportation
Officials (AASHTO), four states that allow LCV operations, and four
state turnpike authorities. We discussed bridge studies with
consultants, including Dr. Harry Cohen of Cambridge Systematics and
Dr. Fred Moses of the University of Pittsburgh. At our request,
FHWA analyzed National Bridge Inventory data to estimate potential
costs to replace bridges if LCVs were allowed to operate nationwide.
The analysis used two alternative load capacity ratings for
bridges--the conservative inventory rating and an intermediate rating
calculated by FHWA between the inventory rating and the more liberal
operating rating. Unfortunately, FHWA did not provide results using
the operating rating because it said the states had been too
inconsistent in reporting operating ratings to the National Bridge
Inventory. To assess potential diversion of freight from rail to
highways, we reviewed analyses that had been done and, with the help
of our economists, examined the documentation of the Association of
American Railroad's (AAR) Intermodal Competition Model, which was
used in most of these analyses. We also drew on our previous work on
intermodal rail transportation.
Concerning the potential use and benefits of LCVs, we interviewed
officials in the rail industry and 22 trucking companies. To get a
first-hand impression of the uses and operational characteristics of
LCVs, we observed LCV operations in Idaho, Indiana, Ohio, and Utah
and rode in a triple on Interstate Route 15 in Utah. We also drew
upon our previous work. Appendix II lists the states, organizations,
and companies we contacted during this phase of our LCV work. The
bibliography lists the studies we reviewed for this report. We
conducted our review of economic impacts of LCVs from November 1992
through March 1994 in accordance with generally accepted government
auditing standards.
LCVS COULD GENERATE SUBSTANTIAL
INFRASTRUCTURE COSTS UNLESS THEIR
OPERATIONS ARE RESTRICTED TO THE
MOST SUITABLE HIGHWAYS
============================================================ Chapter 2
There has been wide disagreement on the magnitude of potential
infrastructure costs that could result from nationwide LCV
operations. FHWA has made estimates of about $2.2 billion to $3.5
billion, while a study done for the trucking industry made lower
estimates and one done for the railroad industry made higher
estimates. Analyses of the potential impact of LCVs on the highway
infrastructure have assumed that they would operate nationwide on the
interstate system and on at least some primary highways. If allowed
this broad scope of operations, LCVs could generate substantial
infrastructure costs--primarily for bridge replacement, interchange
widening, and the provision of staging areas for breaking down and
assembling LCVs. Infrastructure costs could also increase if LCVs
diverted freight from railroads to highways. Much of the projected
cost would be incurred if LCVs were allowed to operate in the more
densely populated areas of the country. However, the cost would be
significantly reduced if LCV expansion were limited to carefully
selected routes away from major population areas.
LCVS SHOULD NOT INCREASE
PAVEMENT WEAR
---------------------------------------------------------- Chapter 2:1
Although LCVs operate at substantially higher gross vehicle weights
than truck combinations that are legal nationwide, their impact on
pavement (as well as bridges) is mitigated by the length and number
of axles over which the weight is spread. Because pavement wear is
related primarily to axle loads, LCVs should not increase pavement
wear as long as axle load limits are not increased. In fact, LCVs
may reduce pavement wear from drive axles because they reduce the
number of tractors on the highway. Also, LCVs often operate below
axle load limits because of state regulations that limit their
overall gross weight.
According to engineering principles of AASHTO, pavement wear (as
distinct from environmental damage) results primarily from repeated
passes of heavily loaded axles. As axle loads increase, the damage
to pavements in the form of rutting and fatigue cracking increases
exponentially to the fourth power.\1 The Surface Transportation
Assistance Act of 1982 set weight limits on the interstate system at
20,000 pounds on a single axle, 34,000 on a tandem axle, and retained
the 80,000-pound gross vehicle weight limit. As illustrated in
figure 2.1, a five-axle tractor-trailer weighing 80,000 pounds might
weigh 12,000 on the steering axle and 34,000 on each of the two
tandem axles.
It should be noted that both LCVs and conventional trucks often
operate at less than maximum axle loads when they are carrying
lighter-weight cargo. In addition, LCVs often operate below legal
axle loads because states have limited their gross weights. State
regulations have often limited turnpike doubles to 129,000 pounds or
less, resulting in average loads of less than 30,000 pounds on each
of the four tandem axles. (See fig. 2.1.) In 1986, FHWA calculated
that turnpike doubles weighing 129,000 pounds would cause 24 percent
less pavement damage per thousand cargo tons than single-trailer
combinations at 80,000 pounds. Rocky Mountain doubles weighing
111,000 pounds were calculated to cause 3 percent less pavement
damage.
Figure 2.1: Axle Loads of
Three Truck Configurations at
Likely Maximum Gross Weights
(See figure in printed
edition.)
Note: In actual practice, axle loads will vary somewhat because of
uneven trailer loading.
If heavily loaded, triples could be more damaging than five-axle
tractor-trailers because they use single axles rather than tandems
under their shorter trailers. (The same could be said of the double
28-foot trailers that triples would replace, but triples would use 33
percent fewer tractors.) However, the federal bridge formula would
limit the triple in figure 2.1 to a gross weight of 115,000 pounds,
and several states impose lower limits. At the gross weights shown
in figure 2.1, triples would have comparable axle loads to single,
80,000-pound combinations, and turnpike doubles would average lower
axle loads.
--------------------
\1 The calculations differ somewhat for concrete pavements, which are
more rigid than asphalt pavements. If the thickness of asphalt
pavements is increased, they can hold up better to axle loadings.
LCV EXPANSION COULD GENERATE
ADDITIONAL BRIDGE COSTS
---------------------------------------------------------- Chapter 2:2
Nationwide use of LCVs could generate additional costs to reconstruct
bridges because the gross weights of LCVs may exceed levels
considered safe on some bridges. There is substantial disagreement
on the amount of these costs because analysts have made different
assumptions about the appropriate margin of safety to allow for loads
crossing a bridge. The larger the safety margin used, the greater
the number of bridges that would be considered inadequate for the
heavier gross weights of LCVs.
Heavy loads put stress on the horizontal members of bridge spans,
with maximum bending stress occurring at the center of a span. In
designing the strength of horizontal members, an engineer must take
account of the length of the spans and the amount of load expected to
be exerted on each span. The highest anticipated load includes both
the dead weight of the bridge itself and the live load of vehicles
passing over it. In calculating live load, a factor is included to
account for dynamic load increases caused by high speeds, poor
suspensions, or the roughness of pavements. Once the highest
anticipated load is calculated, a margin of additional strength is
designed into the bridge as a contingency. This margin is
substantial, reflecting uncertainty about the actual strength of
materials in the bridge and about what loads might actually occur on
the bridge--illegal overweight trucks, permitted overweight trucks,
or simultaneous loading by multiple trucks.
As seen in figure 2.2, a load that is concentrated over a short
distance is potentially more damaging than a load spread over a
longer distance. For this reason, a vehicle's weight is regulated
not only by gross weight and axle load but also by a bridge formula.
A bridge formula allows more gross weight as the vehicle's wheel base
lengthens. In other words, longer trucks can safely carry more
weight over bridges than shorter trucks. This gives LCVs an
advantage on short-span bridges, but as span length increases, an
LCV's weight is more concentrated relative to the length of the span.
Interestingly, bridges with very long spans must be designed to
support such a heavy dead load that the live load of vehicles becomes
less of a factor.
Figure 2.2: Heavy Short and
Long Trucks on a Bridge Span
(See figure in printed
edition.)
Source: FHWA.
State transportation agencies rate bridges to determine what loads
they can accommodate with acceptable risk. Some states use the most
conservative approach, called the inventory rating. Under the
inventory rating, no vehicle should produce a stress in a bridge
member greater than 55 percent of yield stress.\2 However, AASHTO's
guidelines permit states to use stress levels as high as 75 percent
of yield stress (the operating rating) to analyze bridge capacity,
and at least 26 states do so.
Several analyses have been done of the National Bridge Inventory,
which contains data submitted by the states, to estimate the
potential need for bridge replacements if LCVs (or other heavier
trucks) were allowed to operate nationwide. We noted only two
studies that focused clearly on LCVs to the exclusion of other
changes in weight limits. One, sponsored by the AAR, used the
conservative inventory rating and estimated that LCVs would place
many rural interstate bridges at risk. FHWA did an analysis in 1991
using an intermediate rating equivalent to 65 percent of yield stress
and found a much lower impact from LCVs. We asked FHWA to update its
analysis with recent bridge data and also to generate comparative
results using both the inventory and operating ratings.
Unfortunately, FHWA could not use the operating ratings in the
database because states had not reported them consistently.
Key results of FHWA's analysis for turnpike doubles and triples
combined are shown in table 2.1. The table shows in the middle
column the replacement costs for bridges with inadequate capacity
ratings for currently legal trucks. Using FHWA's intermediate
rating, the estimated cost to replace those bridges is $428 million
for rural interstates and $2.1 billion for urban interstates. The
additional cost to replace bridges rated inadequate for LCVs, shown
in the right column, is estimated at $248 million for rural
interstates and $1.1 billion for urban interstates. If the inventory
rating is used, as in the study sponsored by AAR, bridge replacement
costs attributable to LCVs are estimated at over $5 billion for rural
interstates and over $13 billion for urban interstates.
Table 2.1
How Bridge Cost Estimates Vary With
Different Ratings
(Dollars in millions)
Additional costs
Bridge replacement for turnpike
Bridge rating costs for current doubles and
criteria\a trucks\b triples\b
-------------------- ------------------ ------------------
Intermediate rating
Rural interstates $ 428 $ 248
Urban interstates 2,125 1,078
============================================================
Total 2,553 1,326
Inventory rating
Rural interstates 819 5,095
Urban interstates 3,444 13,234
============================================================
Total 4,263 18,324
------------------------------------------------------------
\a The inventory rating is 55 percent of yield stress, the
intermediate rating is approximately 65 percent, and the operating
rating (not used in the analysis) is 75 percent. AAR has sponsored a
study using the inventory rating to project the impact of LCVs on
bridges. The majority of states use the operating rating to post
bridges, and FHWA calculated this intermediate rating to make what it
considered a reasonable estimate of potential bridge replacement
costs.
\b Bridge replacement costs were calculated from the unit costs
furnished by the states in 1993. FHWA's results are for a turnpike
double weighing 129,000 pounds and a triple weighing 115,000.
Source: FHWA analysis of National Bridge Inventory for GAO (1993).
The experts we consulted considered it reasonable to use the
operating rating or FHWA's intermediate capacity rating in estimating
bridge replacement costs. If the operating rating had been used in
the analysis, projected costs would have been somewhat lower than
those resulting from FHWA's intermediate rating. According to a
survey done for the Transportation Research Board in 1989, 26 of 46
states responding used the operating rating to determine legal load
limits for bridges, 8 states use the inventory rating, and 12 use an
intermediate rating. It is thus reasonable to conclude that LCVs
would not require bridge replacement costs any higher than those
estimated by FHWA when it used its intermediate rating.
Since states differ in their choice of ratings to use in establishing
legal load limits for bridges, it could be expected that some states
would not consider any of their bridges to be at risk from LCV
operations. The turnpike and state officials we interviewed did not
believe that LCV operations had adversely affected any of their
bridges.
According to FHWA, there were 54,161 bridges in the interstate system
in 1992. On the basis of state inspection reports, 3,697 were
considered structurally deficient, and 10,028 were considered
functionally obsolete. State estimates of the backlog of work needed
on all interstate bridges in 1992 totaled $22.7 billion. Combining
FHWA's estimated replacement costs in table 2.1 for rural and urban
interstates, the impact of LCVs would total about $1.33 billion,
involving 680 bridges.\3 An FHWA official did not believe these
bridges were among the deficient and obsolete bridges identified
through the state inspections. It can be seen in table 2.1 that
confining LCVs to rural interstates would significantly moderate
their cost impact on bridges. The impact could be further reduced by
allowing LCVs only on highways where all or most bridges are capable
of accommodating them with an acceptable safety margin.\4
--------------------
\2 Yield stress is the load level at which a bridge component would
yield and become deformed.
\3 An FHWA official pointed out that replacing bridges to accommodate
LCVs would also generate substantial costs to the public in the form
of delays, increased fuel usage, and pollution during reconstruction.
FHWA is sponsoring a study to develop a method for estimating such
costs.
\4 FHWA cautioned that its analysis was intended to provide a
reasonable estimate of potential bridge cost impacts of national LCV
use, not to pinpoint bridges needing replacement. States must
individually inspect and evaluate bridges to determine the loads they
are capable of supporting on a regular basis.
INTERCHANGE RECONSTRUCTION AND
STAGING AREAS COULD BE COSTLY
IF EXTENSIVE ACCESS TO THE
INTERSTATE SYSTEM IS DESIRED
---------------------------------------------------------- Chapter 2:3
The longer LCVs have difficulty negotiating some interchange ramps
and also need staging areas where they can be assembled or broken
down for delivery as shorter combinations. Modifying interchanges
and building staging areas to provide LCVs regular access to and from
the interstate system could be a costly undertaking, depending on the
number of access points deemed necessary. Options exist for lowering
these infrastructure costs, such as restricting LCV access points to
those most needed and allowing the trucking industry to provide its
own staging areas, as some western states have done.
Because of their length, some LCVs off-track, or "cut corners," more
than single combinations. This restricts their ability to negotiate
intersections and is a reason for confining LCVs to interstate or
other major highways. Because of off-tracking, the longer LCVs also
have difficulty with some interchange ramps. Turnpike doubles have
the most problems with off-tracking. Triples, with their short
trailers, can maneuver better around curves than turnpike or Rocky
Mountain doubles (or even 48- and 53-foot single trailers) and can
thus negotiate many interchanges without causing damage. Figure 2.3
illustrates the difficulty that a turnpike double has with cloverleaf
interchanges and the better tracking of a triple. According to a
survey done by AASHTO in 1985, state highway officials estimated that
as many as 75 percent of the interchanges on the interstate system
were inadequate for turnpike doubles, 66 percent were inadequate for
Rocky Mountain doubles, and 57 percent were inadequate for triples.
It should be noted that respondents considered half the current
interchanges to be inadequate for 48-foot trailers as well.
According to a study for the Trucking Research Institute, many of
these access problems are in densely populated areas of the eastern
United States.
Figure 2.3: Triple and
Turnpike Double on Cloverleaf
Interchange
(See figure in printed
edition.)
Staging areas, either on or off the interstates, would be needed for
LCVs, depending on the access they are allowed to other primary
highways. A staging area is simply a parking lot where LCVs can be
broken down or assembled, so that pickup and delivery to customers
can be done with shorter combinations. Figure 2.4 shows triples at
staging areas on the Ohio Turnpike. Triples operation could be
expanded with few new staging areas. LTL and package delivery
companies often stage triples at their own terminals, which are
usually located near interchanges outside metropolitan areas. LTL
terminals serve as collection and distribution points for small
shipments, and triples can be used for linehauls between terminals in
the same way that double 28-foot trailers are used. Truckload
companies, however, would need staging areas to assemble and break
down turnpike doubles. Truckload companies do not organize their
trips with terminals but rather travel from customer dock to customer
dock. They would have to bring loads by single trailer to a staging
area, combine them into a turnpike double, and then deliver them by
single trailer at the end of the linehaul.
Figure 2.4: Assembly of
Triples at an Ohio Turnpike
Staging Area
(See figure in printed
edition.)
(See figure in printed
edition.)
In 1985, FHWA estimated the nationwide cost of improving interchange
ramps and building staging areas for LCVs at between $750 million and
$2.2 billion, depending on the number of access points to the
interstate system deemed necessary. FHWA's estimate was not based on
a site-specific analysis but, rather, estimated the number of access
points needed by assuming regular spacing in rural areas and relating
the number of urban access points to the size of urban areas. A 1990
study for the Trucking Research Institute pointed out that a number
of western states and several eastern turnpikes were already
accommodating LCVs with either public or private staging areas. This
study concluded that the practical demand for staging areas and
access points would actually be much less than assumed in FHWA's
analysis and that staging areas could be built by the trucking
industry itself.
As is the case with bridges, the cost impact of staging areas and
interchange improvements is related to the types of LCVs that are
allowed and the extent of the highway network open to them. Cost
would be greatest in heavily populated areas. Restricting LCVs to
those routes most suitable for their operation, such as rural
interstates mainly west of the Mississippi River, would significantly
reduce both the costs and benefits projected from LCVs' use
nationwide.
STATE AND TURNPIKE OFFICIALS DO
NOT VIEW LCVS AS COSTLY TO
INFRASTRUCTURE
---------------------------------------------------------- Chapter 2:4
We discussed infrastructure impacts with officials of four states and
four state turnpike authorities that allow LCVs. Most had not done
actual studies of impact and could not cite any evidence that LCV
operations had increased pavement damage. Nevada, however, had
observed that LCVs were averaging higher axle loads in the state than
conventional tractor-trailers and, consequently, were assumed to be
causing more pavement damage. Some state officials believe LCVs have
beneficial effects on the highways because they reduce the number of
truck tractors needed. The Oregon Department of Transportation
estimated in 1992 that if triples were banned in a state referendum,
the resulting increase in trucks on state highways would generate
$2.5 million annually in additional pavement costs.
None of the officials contacted cited any examples of bridge damage
from LCV operations. Idaho had done specific analyses of the bridges
on its LCV network and concluded that all were capable of safely
accommodating vehicles up to at least 129,000 pounds. With regard to
staging areas, the turnpike authorities had provided them, while the
western states had generally left this to the trucking interests.
POTENTIAL DIVERSION OF FREIGHT
FROM RAIL TO HIGHWAY DOES NOT
APPEAR SIGNIFICANT
---------------------------------------------------------- Chapter 2:5
If LCVs diverted freight from rail to highway, pavement wear could
increase, resulting in additional infrastructure costs. We
identified five estimates of diversion, four of which were based on a
computer simulation model of rail-truck competition maintained by the
AAR. We have reservations about the usefulness of the model, which
are discussed in appendix I. There are also reasons to believe that
turnpike doubles, viewed as the principal source of diversion, will
not be as widely used as assumed. Considering this, the substantial
recent improvements in railroads' productivity, and the trend of
intermodal cooperation between railroads and truckload companies, it
is unlikely that selective expansion of LCV routes would have a
significant impact on rail traffic.
The existing estimates of rail diversion used differing assumptions
about such variables as the amount of cargo weight that turnpike
doubles would carry and the extent of the highway network they would
be allowed to use. As seen in table 2.2, the various analyses have
projected that LCVs would divert from 4 to 11 percent of rail
ton-miles of cargo, increasing trucking ton-miles from 5 to 16
percent.
Table 2.2
Analyses Projecting That LCVs Would
Divert Freight From Railroads,
Increasing Use of Highways
Waybill Rail ton- Increased
sample miles trucking
Source of Type of used\a diverted ton-miles
study LCV (year) (percent) (percent)
-------------- -------- ---------- ---------- ----------
Association of Turnpike 1988 11 16
American doubles
Railroads
Association of Turnpike 1990 10 14
American doubles
Railroads
Department of All LCVs 1981 9 12
Transportation
Transportation Turner 1987 4 6
Research Trucks\b
Board
Trucking Turnpike 1987 4 5
Research doubles
Institute\c
------------------------------------------------------------
Note: Some differences occur because of rounding.
\a The waybill sample is a sample of rail shipments reported to the
Interstate Commerce Commission.
\b The Transportation Research Board published in 1990 a study of the
"Turner Trucks," hypothetical intermediate single and double
combinations with extra axles to allow additional weight to be
carried.
\c The Trucking Research Institute is an affiliate of the American
Trucking Associations Foundation.
AAR views turnpike doubles, which would be used by truckload
companies, as the principal LCV threat to rail traffic. However, as
explained in more detail in chapter 3, the truckload companies would
have to significantly change their mode of operation to use turnpike
doubles. None of the large truckload companies we contacted were
currently using turnpike doubles in the absence of a national network
open to them, except for one company that reported occasional use.
Instead, such companies have increasingly turned to 53-foot trailers
and intermodal rail service to improve productivity. If LCV route
expansion occurred piecemeal, in only certain areas of the country,
there would be few opportunities to use turnpike doubles as an
alternative to rail traffic.
On the other hand, LTL and package companies could expand their use
of triples even with selective additions to the LCV network. These
companies do not compete directly with railroads, but they do use
intermodal rail service for some longer trips as well as for seasonal
surges in traffic and for managing unbalanced markets. If triples
could be used on a wider basis, some of these intermodal shipments
might return to the highway. However, the LTL companies account for
a very small percentage of intermodal rail business, so they would
have little impact on rail ton-miles. The dominant package carrier
that has been a major intermodal customer for many years told us that
it has no intention of changing its basic intermodal strategy.
Company officials said they would use triples to complement rather
than replace their intermodal service.
The estimates based on AAR's model are susceptible to the limitations
of the model, which are discussed in detail in appendix I. The
fundamental problem with these analyses is that they used data from
past years and assumed that turnpike doubles were introduced to
compete for rail traffic while railroad productivity remained the
same. In recent years, however, railroads have won labor concessions
that have significantly reduced their costs. They have improved
their technology and service, and truckload companies have
increasingly sought to reduce their costs by using intermodal rail
service for longer hauls.
The president of AAR has pointed out that railroads have had the most
gains in productivity in the past 5 years of any of the 176
industries tracked by the Bureau of Labor Statistics. Intermodal
shipments increased 134 percent and carload ton-miles 22 percent from
1980 to 1993, despite the transition of the truckload industry to
48-foot and increasingly to 53-foot trailers. It is possible that
railroads would have captured more market share had the longer
trailers not been allowed. However, considering the improving
competitive position of the railroads and the obstacles to general
use of turnpike doubles, it does not appear that selective expansion
of LCV routes would significantly affect rail traffic.
LCV ROUTE EXPANSION WOULD HAVE
VARYING IMPACTS ON THE TRUCKING
INDUSTRY AND ITS CUSTOMERS
============================================================ Chapter 3
Expansion of the routes open to LCVs would benefit some sectors of
the trucking industry more than others. LTL and package companies
could derive an immediate benefit from even a partial expansion of
routes. Officials of large truckload companies, however, see little
opportunity in using turnpike doubles in the absence of a nationwide
highway network open to them. Even with such a network, it is
questionable whether turnpike doubles would be widely used in the
truckload industry. Small companies and owner-operators would have
particular difficulty in managing the logistics of operating doubles.
In some situations, however, small truckload companies and private
fleets have used turnpike doubles or Rocky Mountain doubles
profitably, and selective expansion of LCV routes would probably
create some new opportunities.
LTL COMPANIES COULD IMMEDIATELY
BENEFIT FROM LCV EXPANSION
---------------------------------------------------------- Chapter 3:1
As discussed in our previous reports on LCVs, triples are used
primarily by large national and regional LTL and package companies.
On the Ohio Turnpike, for example, four of these companies accounted
for 82 percent of the tractor permits issued for operating triples.
Such companies use hub-and-spoke terminal systems to gather and
distribute the small freight shipments they specialize in, and they
have found the 28-foot trailer to be the most useful container for
organizing shipments between terminals. They routinely use twin
28-foot combinations for this purpose and can easily add a third
trailer wherever these are permitted. LTL company officials told us
that they could benefit from even a piecemeal expansion of LCV
routes.
According to a study done for the Trucking Research Institute,\1 LTL
and package companies would be the principal beneficiaries of any
expansion of LCV routes. However, because a majority of the expenses
of these companies involves collecting, consolidating, sorting, and
distributing functions, the savings derived from using triples
between terminals are small compared with total revenues. The
authors of the study estimated that triples would reduce LTL and
package company costs by $1.1 billion in 1988 dollars if used on
interstates and some primary highways. This would represent just
over 4 percent of the $26.6 billion in LTL and package company
domestic revenues reported in 1988. The following are two examples
of how LTL and package companies told us they benefit from using
triples:
Company A, a nationwide LTL company, operates triples about 15
million miles a year in 14 states. This results in a
7.5-million-mile reduction in vehicle miles traveled and a fuel
saving of 900,000 gallons. The company estimated its current
savings from triples at $12 million a year, or about 0.5 percent
of its $2.2 billion in 1992 revenues.
Company B said its triples have average axle loads that are more
than 4,000 pounds below the legal limits and use 27 percent less
fuel than other combinations for the same amount of cargo. The
company estimated its savings from triples at $30 million a year
and believed this would reach $100 million if triples were legal
nationwide. Had the $100 million been saved in 1992, it would
have represented 0.8 percent of the company's $12.6 billion in
revenues.
These current and projected savings from triples operation are thus
not a large percentage of the industry's revenues. From the
perspective of an individual company, however, the savings could be
important if they helped improve profitability. The LTL industry has
experienced considerable pressure on its profit margins in recent
years and would welcome an opportunity to make wider use of triples.
--------------------
\1 SYDEC, Inc., and Jack Faucett Associates. Productivity and
Consumer Benefits of Longer Combination Vehicles. Final Report
Submitted to the Trucking Research Institute. Arlington, Va.: May
14, 1990.
WIDE USE OF TURNPIKE DOUBLES
APPEARS UNLIKELY
---------------------------------------------------------- Chapter 3:2
Certain characteristics of the truckload industry favor the use of
single tractor-trailer combinations because of their flexibility.
Large truckload companies have made little use of turnpike doubles in
the absence of a national network of highways open to them. A number
of truckload companies have sought productivity improvements from
using longer trailers and from intermodal cooperation with railroads.
It seems unlikely that LCV route expansion, if done selectively by
states, would result in significant growth in the use of turnpike
doubles. Some new routes might present opportunities for successful
use of turnpike doubles, and some additional uses might be found for
Rocky Mountain doubles.
LARGE TRUCKLOAD COMPANIES DO
NOT CURRENTLY USE TURNPIKE
DOUBLES
-------------------------------------------------------- Chapter 3:2.1
Truckload companies generally sell their service by the trailerload,
quoting a price per mile from the shipper's dock to the consignee's
dock. While truckload companies may have some regular round-trip
business on major routes, often their drivers progress around the
country picking up and delivering a sequence of loads before
returning home. This is done in order to minimize the miles traveled
empty. Truckload freight is often time-sensitive, especially as
manufacturers and distributors have increasingly emphasized
just-in-time deliveries to reduce inventories. These factors would
make it somewhat difficult to effectively use turnpike doubles, which
would require truckload companies to restructure their operations
into major linehaul routes with feeder runs by single-trailer
combinations.
In some situations, truckload companies have found profitable uses
for double or even triple combinations. However, none of the large
companies we contacted were using turnpike doubles in the current
situation (one company mentioned occasional use). Some pointed out
that without a national network of highways open to turnpike doubles,
it is not practical to realign operations in order to use doubles.\2
They also noted that under pressure from customers, many companies
are transitioning to 53-foot trailers. Even if the interstate system
were open to turnpike doubles, the following questions would remain
about their use:
Would customers accept a return to 48-foot trailers?
Would enough interchanges accommodate turnpike doubles to give them
sufficient access to markets?
How long would a linehaul have to be to generate enough savings to
compensate for the cost of managing extra drivers and tractors
in feeder service?
Would turnpike doubles be able to compete in long hauls with
intermodal rail service?
How often could loads be combined--from a single customer or two
customers--and still meet expectations of timely delivery?
Several company officials pointed out that competition and customer
demands drive the service they offer. If a competitor began
successfully using turnpike doubles in a particular corridor, other
truckload companies would be forced to use them as well. This type
of competitive pressure is currently causing many truckload companies
to offer intermodal rail service as a way to reduce costs and to
reduce drivers' long absences from home. With the current fragmented
network of highways open to turnpike doubles and the improbability of
a federally mandated national LCV network, it appears that truckload
companies are seeking other ways to improve productivity. An
official of the Interstate Truckload Carriers Conference said that
while widespread use of turnpike doubles was unlikely, some corridors
might be suitable for their use and would contribute to national
productivity.
--------------------
\2 The study done for the Transportation Research Board of the
hypothetical Turner Truck, an intermediate double with extra axles
for additional weight, reported skepticism from truckload carriers
similar to the logistical concerns we heard.
SOME SMALLER COMPANIES AND
PRIVATE FLEETS FIND LCVS
USEFUL
-------------------------------------------------------- Chapter 3:2.2
In the western states, there are numerous examples of small trucking
companies that use Rocky Mountain doubles or some type of long double
configuration to haul minerals, gravel, bulk liquids, asphalt, or
similar products on regular routes. Oregon, for example, has
permitted 1,200 different companies to use Rocky Mountain doubles.
Figures 3.1 and 3.2 show LCV configuations used for special hauling
purposes in Idaho. Small companies may find specific situations
where the regularity of round trips and relatively short hauls makes
it practical and profitable to use some form of LCV. However, for
wide area operation, the logistical problems that would confront
large truckload companies in managing doubles, such as organizing
pickup and delivery with staging areas, would be even more difficult
for smaller companies. Similarly, the Owner-Operator Independent
Drivers Association views turnpike doubles as a threat to its members
and opposes lifting the freeze on LCV routes.
Figure 3.1: Dry Bulk Trailers
in Idaho Configured as Rocky
Mountain Double
(See figure in printed
edition.)
Figure 3.2: Turnpike Double
Configuration Used by Paving
Company in Idaho
(See figure in printed
edition.)
As mentioned in chapter 1, private fleets are maintained by many
companies to serve their own transportation needs. They are likely
to have regular routes, and it is not uncommon for their trucks to
return empty from trips. For these reasons, some private fleets find
it worthwhile to use LCVs where they are legal. We discussed private
fleet operations with two grocery distribution companies, a snack
food company, and a company that supplies paving materials. One of
the grocery distributors was using both turnpike and Rocky Mountain
doubles to deliver to stores in rural areas in the West. Company
officials believe their costs would increase 25 percent if they could
not use LCVs. The snack food company was operating on the Kansas
Turnpike, and its light-weight cargo filled trailers long before
reaching their maximum weight. Officials said the extra cargo space
provided by turnpike doubles generated considerable cost savings.
Figures 3.3 and 3.4 show LCVs used in private fleets.
Figure 3.3: Turnpike Double
Used by Private Fleet on Ohio
Turnpike
(See figure in printed
edition.)
Figure 3.4: Rocky Mountain
Double Used by Private Fleet in
Utah
(See figure in printed
edition.)
WIDER USE OF LCVS WOULD LIKELY
RESULT IN LOWER FREIGHT
CHARGES, BUT THE OVERALL EFFECT
WOULD BE SMALL
---------------------------------------------------------- Chapter 3:3
Even if LCVs were allowed nationwide, their potential use would not
have a large impact on overall trucking costs. Whether the savings
achieved would result in lower freight charges and eventual benefits
to consumers would depend on the intensity of competition between
trucking companies. Recent experience in the trucking industry
suggests that much of the cost savings would be passed through,
probably in the form of discounts.
A 1990 study for the Trucking Research Institute estimated that
opening the interstate system and some primary highways to LCVs would
lower the nation's annual trucking costs by $3.4 billion, or 2.8
percent, by 1995. This included $716 million in savings from
turnpike doubles, an estimate that seems optimistic, considering the
problems the truckload industry would face in using them. While it
may seem surprising that LCVs would not have a greater impact on
overall trucking costs, it should be recognized that these longer
vehicles would be used essentially for linehauls on interstate
highways. For shipments that involve substantial mileage on other
highways with single trailers, the use of LCVs for the linehaul
portion of the trip may not reduce total costs very much.
Whether the customers of trucking companies would benefit from LCV
expansion would depend on the extent to which competition forces
companies to pass along the productivity savings. There is evidence
that competition has restrained rate increases since the partial
deregulation of trucking in 1980. From 1980 through 1992, revenue
per ton-mile increased only 24 percent in the LTL sector and only 5
percent in the truckload sector. In the same period, consumer prices
increased 70 percent and producer prices 40 percent. Thus, trucking
industry prices lagged behind the general rate of inflation.
One truckload company executive pointed out that deregulation led
initially to overcapacity in the truckload industry, while the
current decade may see more balance between capacity and demand. If
that occurs, truckload companies may not be forced to pass along all
the cost savings but might instead be able to improve their rates of
return. The LTL industry, on the other hand, has continued to
experience price discounting from intense competition. It is
reasonable to expect that this competition would force LTL companies
to pass along to customers a substantial portion of the cost savings
from the use of triples, although the impact on total transportation
costs would be small.
SAFETY CONCERNS MAY JUSTIFY LIMITS
ON LCV EXPANSION
============================================================ Chapter 4
Current LCV use is confined primarily to areas of low traffic density
in the West and certain toll roads in six eastern and midwestern
states. Because of certain operational characteristics, LCVs could
pose greater safety risks than single-trailer trucks if their use
were expanded to more heavily traveled highways. These
characteristics make it important that drivers be well trained and
that trucks be properly maintained and loaded. Our two previous
reports on LCVs noted that little meaningful data are available to
determine LCVs' safety or to monitor their operations. We suggested
that safety could be enhanced by adopting standards for drivers'
qualifications and by assuring that LCVs, especially doubles, receive
an adequate number of roadside inspections.
SOME OPERATIONAL
CHARACTERISTICS OF LCVS
INCREASE THEIR SAFETY RISK
---------------------------------------------------------- Chapter 4:1
LCVs have operating characteristics that can reduce their stability
and maneuverability compared with those of single-trailer
combinations. Stability is more of a concern for triples than for
doubles, but heavier doubles can present problems when merging into
traffic because of their slow acceleration and can also be very
slow-moving on grades.
Triples operating at highway speeds tend to exhibit trailer sway--a
side-to-side movement of their multiple, relatively short trailers.
This can be caused by a driver's sudden steering movements, poor
maintenance of the converter dollies that connect trailers, rutted
highways, or wind gusts. Rearward amplification of trailer
sway--often called the "crack the whip" effect--is usually initiated
when drivers make sudden steering movements to avoid obstacles and is
also more pronounced for triples. The converter dollies used in the
United States have a single connection point with the trailer ahead,
which allows greater trailer sway and rearward amplification than the
dollies with two connection points used in Canada. Turnpike doubles,
with their longer wheelbase trailers and fewer connecting joints, are
more stable than triples, but these heavier LCVs are slower to
accelerate and move with traffic. Unless tractor power is
significantly increased, speed differentials can present a hazard in
traffic, especially on grades.
There has been some disagreement about LCVs' stability during braking
and the distance required to stop. Under controlled test conditions
with experienced drivers, recommended equipment, properly adjusted
brakes, and properly distributed loads, LCVs have been shown to stop
in fairly short distances--comparable to single-trailer trucks. Part
of their recommended equipment is a device that allows brakes on the
rear trailer to be applied first, thus "stretching" the vehicles to
facilitate a straight stop. Under less-than-ideal conditions,
however, LCV braking can be less effective. Out-of-adjustment
brakes, the most commonly found defect in roadside inspections, would
be more serious for LCVs because of the greater number of brakes that
must be properly adjusted and must work in proper sequence. Also, if
the last trailer is empty or lightly loaded, chances are greater that
the trailer's brakes will lock and cause it to swing out to the side.
DATA ON LCV SAFETY ARE LIMITED
BUT HAVE NOT SHOWN A PROBLEM ON
CURRENTLY AUTHORIZED ROUTES
---------------------------------------------------------- Chapter 4:2
Many traffic databases fail to identify LCV configurations, making it
difficult to determine their safety record. The limited data
available from a few states and several large companies indicate that
LCVs have not been a safety problem on the turnpikes and western
highways where they have operated. Whether this record could be
maintained in heavier traffic is open to question.
We reported in March 1992 that efforts to study the accident rates of
multiple-trailer trucks had reached differing conclusions concerning
the safety of LCVs. Weaknesses in the data at both the national and
state levels as well as differing study approaches contributed to the
differences. For example, the lengths of trailers are rarely
recorded on accident forms, making it impossible to separate
accidents involving turnpike or Rocky Mountain doubles from those
involving the double 28-foot trailers operated nationwide. Also,
very little mileage data on LCVs are available, thus making it
difficult to compare accident rates of LCVs with those of
single-trailer trucks.
On the basis of the limited data available from a few states and
several large companies, triples appear to have relatively good
safety records. Triples are operated primarily by large national and
regional LTL companies with good safety records and experienced
drivers, mainly on limited-access highways. In contrast, little is
known about the safety of doubles, particularly Rocky Mountain
doubles. The latter are operated by a more diverse group of smaller
companies that often haul a variety of heavier commodities on a wider
network of roads--many of them two-lane roads.
LCV use has generally been limited to less-congested highways. One
or more types of LCVs are currently allowed on less than one-fourth
of the interstate system and about one-fifth of the other highways in
the national truck network. The 1991 average traffic volume on rural
and urban interstates in the 14 western states that allow LCVs was
less than half of that in the remaining states. Except for Rocky
Mountain doubles, LCVs have often been restricted to interstate
highways or other limited-access highways, which have lower accident
rates than other types of highways.
STATE REGULATION OF LCV
OPERATIONS HAS BEEN UNEVEN
---------------------------------------------------------- Chapter 4:3
We reported in November 1993 that the regulation of LCV operations
varies widely in the states that allow LCVs. Few states have
specific requirements for LCV drivers, despite widespread
acknowledgement that experienced drivers are important to LCV safety.
States have not done special inspections of LCVs, and some evidence
suggests that the longer combinations have been underrepresented in
roadside inspection programs.
State officials considered their LCV controls adequate, although data
on which to base this conclusion were limited in most states. While
guidelines from both the Western Highway Institute and the Western
Association of State Highway and Transportation Officials recommend
that drivers be experienced and have good safety records, very few
western states have any special requirements for drivers. In
addition, because traffic citations do not specify vehicle
configuration, states cannot monitor the performance of LCV drivers
and their compliance with permit requirements. FHWA is in the
process of establishing minimum training requirements for LCV drivers
and agreed with us that drivers' experience and driving records
should also be considered.
We reported in November 1993 that most states had not used data from
the roadside inspections performed under the Motor Carrier Safety
Assistance Program to monitor the condition of LCVs or the drivers'
adherence to safety regulations. We found that the out-of-service
rate\1 for doubles combinations exceeded that for all trucks
inspected in 8 of 12 western states, while the rates for triples were
lower. Both doubles and triples appeared to be underrepresented in
roadside inspections, although FHWA argued that further study was
needed to determine whether LCVs were getting adequate attention
under the program.
--------------------
\1 Trucks and drivers are placed out-of-service (not allowed to
continue operating until violations have been corrected) if
violations deemed critical to safe operation are discovered during
roadside inspections.
CONCLUSIONS, MATTERS FOR
CONGRESSIONAL CONSIDERATION, AND
AGENCY COMMENTS
============================================================ Chapter 5
CONCLUSIONS
---------------------------------------------------------- Chapter 5:1
Any decision to allow the use of LCVs involves safety concerns as
well as economic factors. While LCVs may require some additional
public investment in the highway infrastructure, these costs appear
to be exceeded by the recurring annual benefits in the form of lower
transportation costs. The safety issues are less easily answered.
As we have previously reported, the apparently good safety record of
LCVs to date must be viewed in the context of the less-congested
highways where they have operated and the use of triples mainly by
large LTL and package companies with good safety records. A wider
use of LCVs could bring them in proximity of major metropolitan areas
and on more-heavily traveled highways, which would entail greater
risks to the passenger traffic with whom trucks share the highways.
Analyses that have addressed the costs and/or benefits of LCVs have
assumed that these longer combinations would operate on a national
network of highways. If, for safety reasons, LCVs were kept off the
more-congested highways east of the Mississippi River, this would
significantly reduce both the infrastructure costs and potential
benefits from LCVs. The most favorable cost-benefit ratios could be
achieved through selective designation of suitable routes, taking
account of traffic density, the capacity of bridges, the adequacy of
interchanges, and the need for staging areas. To the extent that
additional infrastructure costs are identified, states must decide
how to recover them.
Triple-trailer combinations would show the most obvious economic
benefit under selective route expansion because (1) they can be
accommodated more easily by the existing infrastructure, (2) they can
often operate out of company terminals with few new staging areas,
and (3) LTL and package companies could expand the use of triples
incrementally if additional states authorized them. Specific,
limited uses can be found for turnpike doubles in a fragmented
network, but substantial use of these combinations would require a
national network of highways open to them. Even with such a network,
it is questionable whether these long doubles would be a viable
alternative to the current trends in the truckload industry, which
involve using longer single trailers and intermodal rail service.
MATTERS FOR CONGRESSIONAL
CONSIDERATION
---------------------------------------------------------- Chapter 5:2
Considering the need for additional infrastructure investment and the
uncertainties about the safety of LCVs, we believe that if the
Congress wishes to allow expanded use of LCVs, it should authorize
the Secretary of Transportation to consider exceptions to the freeze
on LCV expansion only if requested by states and accompanied by the
following:
A state analysis of each proposed route to demonstrate its
suitability in terms of the density of traffic, condition of
bridges, and adequacy of interchanges. States should determine
whether additional infrastructure costs would be generated and
how these costs would be recovered.
A certification that the state will enforce qualification standards
for LCV drivers, ensure adequate inspection of LCV equipment,
and monitor the experience of LCVs to identify any emerging
safety problems or negligent carriers.
AGENCY COMMENTS
---------------------------------------------------------- Chapter 5:3
We provided copies of the draft report to DOT officials, who chose to
provide oral comments. We met with various DOT officials, including
the Director, Office of Engineering and Highway Operations Research
and Development, FHWA, and the Chief, Office of Economic Analysis,
FRA. These officials generally agreed with the report's findings,
conclusions, and matters for congressional consideration. They gave
us editorial and technical suggestions for clarifying and qualifying
the report, which we have included in the text where appropriate. On
June 14, 1994, in hearings before the Subcommittee on Surface
Transportation, House Committee on Public Works and Transportation,
the FHWA Administrator stated that FHWA's last study on truck size
and weight was 30 years old and that FHWA would initiate a study to
thoroughly reexamine all commercial vehicle size and weight issues.
EVALUATION OF THE USE OF THE
ASSOCIATION OF AMERICAN RAILROADS'
MODEL IN PROJECTING FREIGHT
DIVERSION BY TURNPIKE DOUBLES
=========================================================== Appendix I
SENSITIVITY OF THE MODEL TO
ASSUMPTIONS
--------------------------------------------------------- Appendix I:1
The Association of American Railroad's (AAR) model uses a sample of
rail shipments reported to the Interstate Commerce Commission and
assumes that for each, an alternative truck movement was available.
Using various sources of data, the model calculates the total
logistics cost to a shipper (payment to the carrier plus other costs
of using rail or truck) and calculates for each shipment a
probability that it would go by rail. The higher the probability
(closer to 1.0), the more likely that all such shipments would go by
rail (coal, for example, would have a high probability). A reduction
in truck costs (such as the ability to use turnpike doubles) would
lower the probabilities, which the model interprets as a directly
proportional shift of traffic from railroads to trucks. For example,
a reduction from 0.57 to 0.53 would represent a 4-percentage-point
loss of the rail traffic in question. The model includes an interim
step in which the railroad may lower its profit margins in an attempt
to retain the business. The impact on railroad revenues is thus
greater than just the loss of ton-miles.
The results generated by the AAR model depend considerably on the
assumptions made about the total logistics costs for rail and truck
moves. For example, assumptions must be made about the highways that
would be open to turnpike doubles, which would affect the amount of
extra cost incurred to assemble pairs of trailers and then deliver
them to customers after their linehaul. Another question is whether
the cost of infrastucture improvements would be recovered from the
operators of longer combination vehicles (LCV), thus decreasing
somewhat the cost advantage they would gain.
Apart from the sensitivity of the model to these kinds of cost
assumptions, an important question arises regarding the extent to
which turnpike doubles would actually be used. A key assumption of
the model is that a trucking alternative (in this case, a turnpike
double alternative) is available for every rail shipment. As
discussed in the body of this report, the truckload industry may not
be as likely to use turnpike doubles as these diversion analyses have
assumed.
LIMITATIONS OF THE MODEL
--------------------------------------------------------- Appendix I:2
As used in the diversion analyses, the AAR model has two basic
limitations. The first is that it is static--it calculates diversion
that would have occurred if the lower-cost truck option had been
available at the time of the rail shipments in the database.
Analysts did not attempt to provide for ongoing competitive
improvements in the rail and trucking industries that would determine
whether future shipments would actually shift to the highway. For
example, many train crews have been reduced from three or four to two
as a result of settlements following a 1991 strike. The model could
apparently be programmed to anticipate changes such as this, but none
of the LCV diversion studies took account of this reduction in rail
costs. Unless the Congress were to mandate a nationwide LCV network,
expansion would likely take place slowly as states designated routes
open to LCVs. Throughout such a period, railroads would have time to
introduce further productivity improvements to counter the threat
from LCVs. While not all improvements would be as dramatic as the
crew reductions, railroads are continually improving such things as
train and car control, locomotive efficiency, and railcar capacity.
In commenting on a draft of this report, a Federal Railroad
Administration official pointed out that each time the AAR model is
run with updated waybill data, the railroad costs reflect
productivity improvements that have occurred. This is true; in fact,
AAR's analysis with 1990 data predicted slightly less diversion than
its analysis with 1988 data. Our point is, however, that whichever
year is chosen, the analyses have held railroad productivity
constant, while introducing a quantum leap in trucking productivity
as if it had already happened. As noted above, this is very
different from what could be expected in the real world.
A second important limitation of the AAR model is that it computes
diversion in only one direction, from railroads to trucks. Since the
model does not have a database of truck shipments comparable to the
waybill sample of rail shipments, it does not compute the amount of
diversion from truck to rail that might occur if rail costs
decreased. The improvements in intermodal rail service that have
occurred in recent years, including the wider use of double-stack
container cars, have helped railroads regain some market share in
long-haul corridors and have led many truckload companies to seek
intermodal relationships with railroads. The AAR model is not
constructed to capture changes such as this that divert freight from
highways to railroads.
ORGANIZATIONS CONTACTED BY GAO
========================================================== Appendix II
FEDERAL AGENCIES
------------------------------------------------------ Appendix II:0.1
Federal Highway Administration
Federal Railroad Administration
Interstate Commerce Commission
National Transportation Safety Board
LCV STATES
------------------------------------------------------ Appendix II:0.2
Idaho
Nevada
Oregon
Utah
TOLL ROAD/TURNPIKE
AUTHORITIES
------------------------------------------------------ Appendix II:0.3
Indiana Department of Transportation,
Toll Road Division
Kansas Turnpike Authority
New York State Thruway Authority
Ohio Turnpike Commission
INDUSTRY ORGANIZATIONS
------------------------------------------------------ Appendix II:0.4
American Road and Transportation
Builders Association
American Shortline Railroad Association
American Trucking Association
Association of American Railroads
Institute of Transportation Engineers
International Bridge, Tunnel
and Turnpike Association
International Brotherhood of Teamsters
Interstate Truckload Carriers Conference
National Industrial Transportation League
National Private Truck Council
Owner-Operator Independent Drivers
Association
Regular Common Carrier Conference
Trucking Research Institute
Western Highway Institute
OTHER ORGANIZATIONS
------------------------------------------------------ Appendix II:0.5
American Association of State Highway
and Transportation Officials
Cambridge Systematics, Inc.
Transmode Consultants, Inc.
Transportation Research Board
SYDEC, Inc.
Texas Research and Development Foundation
LESS-THAN-TRUCKLOAD
COMPANIES
------------------------------------------------------ Appendix II:0.6
Churchill Truck Lines
Roadway Express
United Parcel Service (package company)
Utah-Wyoming Freight Line
Yellow Freight System
PRIVATE COMPANIES
------------------------------------------------------ Appendix II:0.7
Associated Food Stores
Associated Wholesale Grocers
Frito Lay
Idaho Asphalt Supply
TRUCKLOAD COMPANIES
------------------------------------------------------ Appendix II:0.8
Bannock Paving Co.
Best Way Express
Builders Transport
Contract Freighters Inc.
Crete Carrier Corp.
CRST Inc.
Doug Andrus Distributing
Handy Truck Line
Heartland Express
Hi-Way Dispatch
J.B. Hunt Transport
Mercer Transportation Co.
Missouri-Nebraska Express
M.S. Carriers
Schneider National
Swift Transportation
Werner Enterprises
MAJOR CONTRIBUTORS TO THIS REPORT
========================================================= Appendix III
RESOURCES, COMMUNITY, AND
ECONOMIC DEVELOPMENT DIVISION,
WASHINGTON, D.C.
------------------------------------------------------- Appendix III:1
Barry T. Hill, Associate Director
Ronnie E. Wood, Assistant Director
Joseph J. Warren, Economist
CINCINNATI REGIONAL OFFICE
------------------------------------------------------- Appendix III:2
Kenneth R. Libbey, Regional Assignment Manager
James R. Wilson, Evaluator-in-Charge
Linda S. Standau, Senior Evaluator
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